Reopened on feature branch: Fix Postgres Date Add/Sub functions for dynamic values

fixed documentation mismatch

Add getGuidExpression() to AbstractPlatform, already exists in MySQLPlatform

These are internal, automatically-created and shouldn't be considered part of
the schema. They cannot be recreated because of their reserved names.

* The old implementation produced invalid SQLite statements for tables with
  a composite primary key, as SQLite cannot have more than one primary key
  clause and autoincrement can only be declared on a single column
* There is currently no way to tell from its pragma if an SQLite column
  auto-increments, therefore enabling it on all primary keys is not accurate
* SQLite primary keys auto-increment anyway (but slightly differently from an
  actual auto-increment column -- not guaranteed unique)

removedColumns in TableDiff

Mysqli driver: Throw exception if connecting to mysql failed.

bit comparison

Added a LoggerChain

This is now consistent with the naming used in the ORM.

Exclude spatial extension tables

Statement interface change

remove debug output var_dump($firstSchema);

Added mysqli driver.

Portability column forced to lowercase

When using a PDOConnection and the Portability wrapper, the default value \PDO::CASE_NATURAL int(0) and PHP constant CASE_LOWER int(0) got mixed up.

Fixed a few cases of where MysqliStatement::execute() did not throw a exception if a error had a occured.